INTRODUCTION

Both this chapter and the next focus on measurements of the physical and chemical attributes of potential foods that primates select or reject. The major reason for analysing the diets of primate in this manner is to understand the basis for their food choice. Observing primates as they feed quickly raises questions in the observer's mind about the possible foraging strategies that the animals might be following in order to survive. How do primates distinguish food from what is otherwise scenery? Can we measure the attributes of potential foods in the form that primates are actually sensing them? What do primates get out of the foods they choose and are their choices, based on sensory capabilities, optimal in terms of nutrients? Tests of hypotheses that address these questions will require objective dietary analysis. It is important to tailor your measurements to the questions being asked.

The physiochemical characteristics of foods may form important sensory cues for their detection, selection and subsequent processing by primates, but all these characteristics are affected to some degree by specimen storage. Physical characteristics, such as colour, geometry and mechanical properties, are ruined. So it is often important and sometimes vital to make measurements almost immediately, while the specimen is fresh. The alternative of drying specimens for later chemical analysis not only involves a substantial time lag between fieldwork and subsequent access to a laboratory but also can lead to inaccurate results.